MVVM架构~knockoutjs系列之为validation.js扩展minLength和maxLength

    /**
    * 字符串长度-中文和全角符号为2，英文、数字和半角为1
    * @param str
    * @return {Number}
    */
    var getLength = function (str) {
        return Math.ceil(str.replace(/^\s+|\s+$/ig, ‘‘).replace(/[^\x00-\xff]/ig, ‘xx‘).length);
    };
    /**
    * 按字数截取字符串
    * @param str
    * @param len
    * @return {*}
    */
    var subStr = function (str, len) {
        if (!str) {
            return ‘‘;
        }
        len = len > 0 ? len * 2 : 280;
        var count = 0, //计数：中文2字节，英文1字节
            temp = ‘‘;  //临时字符串
        for (var i = 0; i < str.length; i++) {
            if (str.charCodeAt(i) > 255) {
                count += 2;
            }
            else {
                count++;
            }
            //如果增加计数后长度大于限定长度，就直接返回临时字符串
            if (count > len) {
                return temp;
            }
            //将当前内容加到临时字符串
            temp += str.charAt(i);
        }
        return str;
    };
    var checkStrLength = function (str, minL, maxL) {
        var len = getLength($.trim(str));
        var data = {
            ‘checkL‘: (len >= minL && len <= maxL),
            ‘restL‘: maxL - len,
            ‘restStr‘: subStr(str, maxL)
        };
        return data;
    };

    /*扩展的字符长度验证,支持中文占两个字符的空间*/
    kv.rules[‘extMinLength‘] = {
        validator: function (val, minLength) {
            if (!kv.utils.isEmptyVal(val)) {
                console.log(getLength(val));
                console.log(minLength);
            }
            return kv.utils.isEmptyVal(val) || getLength(val) >= minLength;
        },
        message: ‘Please enter at least {0} characters.(extension validator for zzl)‘
    };

    kv.rules[‘extMaxLength‘] = {
        validator: function (val, maxLength) {
            return kv.utils.isEmptyVal(val) || getLength(val) <= maxLength;
        },
        message: ‘Please enter no more than {0} characters.(extension validator for zzl)‘
    };

   self.extName = ko.observable().extend({
                extMinLength: 4,
                extMaxLength: { params: 20, message: "名字太长了" },
     });